Import Oxide engine (Stages 0–10) under MIT license

Full project snapshot migrated to new Gitea remote without history:
engine, editor, physics, script, examples, tests, docs, and assets.
Relicensed from GPLv3 to MIT and updated repo URLs.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

engine/benches/scene.rs

@@ -0,0 +1,58 @@
+//! Benchmark for scene world-transform resolution.
+//!
+//! Stage 3 test criterion: a 10,000-entity scene with a 5-level-deep hierarchy
+//! must resolve all world transforms in under 1ms. The `world_transforms_10k`
+//! benchmark builds exactly that scene and measures a full bulk resolve; check
+//! its reported time against the 1ms budget.
+
+use criterion::{black_box, criterion_group, criterion_main, Criterion};
+use oxide_engine::math::{Transform, Vec3};
+use oxide_engine::scene::{Entity, Scene};
+
+/// Builds a scene of `total` entities arranged as a `depth`-level hierarchy.
+///
+/// Level 0 holds the roots; each subsequent level's entities are distributed as
+/// children of the previous level, so the tree is `depth` levels deep and the
+/// node count is exactly `total`.
+fn build_scene(total: usize, depth: usize) -> Scene {
+    let mut scene = Scene::new();
+    let per_level = total / depth;
+    let mut previous: Vec<Entity> = Vec::new();
+
+    for level in 0..depth {
+        // The last level absorbs any remainder so the count is exact.
+        let count = if level == depth - 1 {
+            total - per_level * (depth - 1)
+        } else {
+            per_level
+        };
+        let mut current = Vec::with_capacity(count);
+        for i in 0..count {
+            let t = Transform::from_translation(Vec3::new(0.01 * i as f32, 0.02, 0.03));
+            let entity = if previous.is_empty() {
+                scene.spawn("n", t)
+            } else {
+                // Spread children across the previous level round-robin.
+                scene.spawn_child(previous[i % previous.len()], "n", t)
+            };
+            current.push(entity);
+        }
+        previous = current;
+    }
+    scene
+}
+
+fn world_transforms_10k(c: &mut Criterion) {
+    let scene = build_scene(10_000, 5);
+    assert_eq!(scene.len(), 10_000);
+
+    c.bench_function("world_transforms_10k_depth5", |bencher| {
+        bencher.iter(|| {
+            let resolved = scene.world_transforms();
+            black_box(resolved.len())
+        });
+    });
+}
+
+criterion_group!(benches, world_transforms_10k);
+criterion_main!(benches);